Ignition harness



Sept. l2, 1950 J. R. FREi IGNITION HARNESS Filed Nov. 2o, 1944 Qin .N

INVENTOR.

fw BY W ATTORNEY Patented Sept. l2, 1950 IGNITION HARNESS Jakob R. Frei, Sidney, N. Y., assigner to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application November 20, 1944, Serial No. 564,325

Claims. l

This invention relates to ignition apparatus and more particularly to radio shielding harnesses, or the like, and parts thereof adapted for use in shielding the conductors of an ignition system for an internal combustion engine.

It has been common and almost universal practice for many years to enclose the ignition distribution systems of aircraft engines in a grounded metallic shield or casing which generally comprises a manifold for a plurality of conductors from which flexible branch conduits for single conductors extend to the individual spark plugs at the cylinders. Most of the failures in shields or harnesses of this character have occurred in the flexible branch conduits which are placed under stress by bending in the initial installation on the engine and which are continuously subjected to severe vibration by wind currents as well as by the unavoidable vibrations of the engine itself. Failure in the shielding conduit generally results in failure of the ignition lead or leads therein and invariably results in radio reception interference. These failures have been prevalent and costly in money, man hours and operating hours, and in most instances have resulted in the loss of personnel and valuable equipment. Accordingly, the problem has had the continuous .attention of the `best brains in the industryV for many years. l

It is therefore one of the objects of the present invention to provide a -novel radio shielding harness for an ignition system and novel parts thereune.

of wherein failures of the above character are minimized or substantially eliminated.

Another object of the invention Ais to provide novel means on a flexible metallic conduit having rigid end pieces whereby the conduit is materiallustration only and are not intended to define the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. l is an isometric view of one type of ignition shielding harness embodying the present invention;

Fig. 2 is a detail sectional view, with parts Ibroken away, showing the free end of one of the flexible spark plug leads of said harness;

Fig. 3 is a detail view, with parts broken away. showing a different type of terminal on the 18- nition conductor within a flexible spark plug lead;

Fig. 4 is an enlarged detail view, partly in section and with parts broken away. of one of said flexible leads; and,

Fig. 5 is a side elevation, partly in section and with parts broken away, showing a modified form of flexible conduit.

The shielding harness illustrated in Fig. 1, by way of example, is adapted for use on an inline engine or on an engine of the type having a plurality of banks of radially disposed cylinders with corresponding cylinders of each bank in As shown, said harness comprises a rigid metallic manifold tube lo which is provided with a plurality of spaced outlets il. Said manifold tube may be of uniform diameter throughout its length.` but 'the same is preferably tapered for the purpose of reducing the weight thereof'and'the space required therefore. Outlets ll may be in the form of rigid metallic tubes extending atan angle to the longitudinal -axis of the manifold tube, the same being soldered or otherwise suitably secured to said manifold tube over openings therein.- The enlarged end vof .rigid tube I0 is preferably mechanically 'and electrically connected with the casing of a distributor or magneto'by means of a flexible manifold sectionl l2, the distributor casing being represented in the drawings by element i4. The latter may be a removable cover for a distributor or magneto casing which may and preferably does have an ignition distributor block or head mounted therein. ends of exible section I2 are preferably soldered or otherwise suitably secured to tube I0 and casing member I4 but the same may be detachably connected at either or both ends in any suitable manner known to the art.

Extending from the outlets Il and from the reduced end of tube I0 are flexible conduits li which house the conductors extending to the individual spark plugs (not shown). Although the flexible metallic portions of conduits I5 may be constructed in any of several well known ways to provide good radio shielding as well as good mechanical strength, the specific type shown in the drawings, by way of example, comprises a flexible tube I6 (Fig. 4) made by interlocking the edges of a spirally wound strip of metal. The flexible tube I6, as shown in Fig. 4, is of the character manufactured by the American Metal Hose Branch of the American Brass Company, but the Titeflex and seamless corrugated types of flexible hose may also be used in practicing the invention. In order to enhance the mechanical strength of hose I6, the same is preferably surrounded by one or more, preferably two, layers I1 of braided or woven metallic strips or wires. The ends of each of the flexible metallic ccnduits I6, I1 extend into rigid metallic ferrules I6, |9 and are suitably secured therein, such as by soldering. Ferrules I8 may be integral with or suitably secured to the outer ends of outlet tubes II and ferrules I9 may be integral with or suitably secured to rigid tubular extensions or elbows 20. As best seen in Fig. 2, the ends of metallic conduit I6, I1 engage an internal shoulder in the ferrules I9 and the construction at ferrules Il may be the same as shown in Fig. 2.

Insulated ignition cables 2| extend from the terminals of the distributor block in casing member I 4 into manifold tube III, I2 and branch out through flexible leads or conduits I6, I1 for conducting high tension current to the spark plugs of the engine. The outer or spark plug ends of each conductor 2| is preferably provided with a plug type connecting terminal which may be of any suitable construction, many of such connectors being well known in the art. In the form shown, the terminal connector for each conductor comprises a flexible insulating tube 22 which extends into elbow 2|), a ceramic or similar tip piece 23 and a spring contact 24. The latter may be constructed to operatively cooperate with threads on the outer end of a metallic sleeve 26 secured to the end of the conducting portion of cable 2|, such as by soldering or crimping. An internally threaded nut 26 may be provided for electrically and mechanically connecting tube to a shielded spark plug in a manner well understood in the art.

In order to prevent chafing of the insulation on cables 20 and to substantially exclude moisture from the interior of the shielding harness, the space around said cables within the abovedescribed shielding casing is preferably, though not necessarily, filled with a flexible solid insulating compound 21. In one suitable embodiment this compound consists of a mixture of polymerized cashew-nut-shell oil and a drying agent, such as formaldehyde or parafrmaldehyde. Other natural or synthetic rubber-like materials may, of course, be used as the filling compound. A spirally cut strip 29 of neoprene or similar material may also be wrapped around each of the cables 20 within conduits I5 to insure adequate spacing of the cables from the inner wall of flexible hose I6.

For the purpose of providing additional insurance against the entry of moisture and other foreign matter into tubes I6, I1 for damping vibrations of said tubes, and for increasing the life of said tubes in various ways, the same are covered in a novel manner. As shown, the covering 29 for each tube |6, |1 consists of a layer of rubber-like material, such as neoprene. Natural rubber or other synthetic elastomers may be successfully used as the covering material. The material of covering 29 preferably fills the spaces between the strands in braided metallic coverings I1 and may penetrate, to some extent, the joints in flexible metal hose I6. With covering 29, it becomes unnecessary to solder or otherwise pack the Joints of hose I6 to prevent the entrance of moisture and the flexibility of the conduits I6 is thereby enhanced. Also, the solid covering 19 prevents the entry of any foreign matter, such as dirt particles, into the woven or braided covering |1, thereby minimizing wear on the latter when it is flexed by bending or vibration.

Although it is not necessary to apply covering 29 throughout the length of each flexible conduit I6, I1, this construction is preferred. The ends of covering 29 extend over and around substantial portions of rigid ferrules I8 and I9. It is this novel feature of the structure shown which substantially prevents breakage of flexible hoses I6, I1 at or near the plane where the same enter said ferrules, i. e., where the breaking of these flexible conduits has been prevalent.

Covering 29 may be applied to hose I6, I1 in any of several ways. For example, when neoprene or similar material is used, the covering may be molded in place by placing strips of unvulcanized neoprene in opposite halves oi a two-part mold, by injecting the covering material into the mold, by wrapping the conduit I6, I1 with strips of sheet neoprene or the like before placing it in a mold, or by any other known method, and then vulcanizing or curing the same. During the curing or vulcanizing process, which takes place under pressure during the application of heat, the covering material is pressed into the spaces in the braided covering I1 and into the joints of flexible hose I6. The metallic conduits may also be successively dipped in a bath of compounded neoprene latex and a coagulating bath of acetone, methane, calcium nitrate, or the like. After several such dippings to provide a covering of suitable thickness, the same may be-dried and vulcanized. Dipping may also take place in a bath of dispersed compounded sheet neoprene, thereby eliminating the necessity of a coagulating bath. Where the nature of the structure permits, extrusion may be resorted to in applying the covering 29. If desired, some suitable known substance, such as cement, may be used to insure good adherence of the covering material 29 to the outer surface of metallic ferrules il and I9. Also, the surface of the ferrules contacted by the covering may be roughened.

In some installations, it may be desirable to make flexible conduits I6 detachable from manifold tube I6. When this is desired, a terminal such as that shown in Fig. 3 may be provided on conduit I5 and conductor 2| for insertion into a socket formed in outlet |I to which the conduits may be secured in a well-known manner by a. nut 99. The sleeve 3| surrounding the terminal end of cable 2| may be similar to tube 22 at the other end of the conduit or the same may be a continuation of the filling compound 21. The socket in the harness manifold for receiving plug 3| may be of any suitable known construction, especially those now in common use on radio shielding harnesses for ignition systems.

If desired, covering 29 may be shaped as shown in Fig. 5 with the radial thickness thereof decreased near the central portion of the conduit. This construction enhances the flexibility of the conduit near the central portion thereof and increases the protection afforded the flexible portion of the conduit near the rigid ferrules at the ends. By thus impeding the flexibility of the conduit near the rigid ferrules substantially all the flexing takes place in the central portion of the conduit where there is less probability of damage resulting from frequent flexing and vlbration.

There is thus provided a novel ignition shielding harness which is more durable under actual operating conditions than similar structures heretofore provided for the same purpose. Said harness comprises a novel flexible shielding conduit which may, per se, be adapted for other purposes and uses. In a simple and inexpensive manner the present invention greatly increases the life and operating efficiency of structures of the type described.

Although only a limited number of embodiments of the invention have been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. For example, different types of terminals may be employed on the flexible leads and a ring manifold may be substituted for manifold I0. Various other changes may also be made in the materials suggested as being suitable and in the design and arrangement of parts illustrated without departing from the spirit and scope of the invention as will now be clear to those skilled in the art. For a definition of the limits of the invention, reference is had primarily to the appended claims.

What is claimed is:

1. In apparatus of the class described, a metallic conduit comprising a rigid metallic tubular section, a flexible metallic tubular section with external surface irregularities and having an end portion thereof extending into the end of said rigid section and soldered thereto, said flexible section including a tube which is corrugated throughout its length and a unitary flexible covering of solid insulation surrounding at least a portion of said flexible section outside of and adjacent to said rigid section and extending into overlapping relation with and around the end portion of said rigid section which surrounds the end of said flexible section, the inner surface o1' said covering having interlocking engagement with the surface irregularities of the flexible section and suflicient adherence to the outer surface of said rigid section to substantially resist relative movement thereof.

2. Apparatus as defined in claim l wherein the flexible corrugated tube comprises a spirally wound strip with interlocking edges.

3. Apparatus as defined in claim l including a conductor extending through said conduit, and flexible solid insulation filling the annular space in said conduit around said conductor.

4. Apparatus as defined in claim 1 wherein an outer tube of interwoven metallic strands surrounds said corrugated tube.

5. Apparatus as defined in claim 4 wherein the material of the covering extends between the strands of said outer tube and into the grooves in the surface of said corrugated tube.

JAKOB R. FREI.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,981,460 Miller Nov. 20, 1934 2,066,473 Jorgensen Jan. 5, 1937 2,105,791 Mascuch Jan. 18, 1938 2,132,326 Stone Oct. 4, 1938 2,134,946 Hurley Nov. 1, 1938 2,173,539 Peters Sept. 19, 1939 2,186,578 Doughman Jan. 9, 1940 2,219,047 Maclachlan Oct. 22, 1940 2,237,490 Knowland Apr. 8, 1941 2,275,019 Peterson Mar. 3, 1942 2,288,918 Parker July '7, 1942 2,338,524 McCabe Jan. 4. 1944 

